Super Enzyme Regulates Testosterone Levels In Male Ruffs

A single gene in the shorebird species known as ruffs controls the blood concentrations of testosterone in males, and this in turn affects their appearances and behavior.

Three adult male Ruffs, Calidris pugnax, are watching a female (out of the picture). The two males with colorful neck plumage are dominant “Independents” whereas the one with white neck plumage is a less dominant “Satellite”. (Credit: Frans Vandewalle / CC BY-NC 2.0)

Ruffs, Calidris pugnax, are medium-sized Eurasian sandpipers that get their common name from the large ruff of feathers that adorn the males’ necks. When raised, this feathery ruff is integral to the males’ ostentatious lekking displays that are intended to attract the attention of the females.